1. Field of the Invention
This invention relates to a jack bar device for retaining cargo in position in a compartment and more particularly to such a device which employs rectangular tubes and which has an expansive adjustment range.
2. Description of the Related Art
Jack bars are commonly used to prevent the shifting of cargo in the compartments of trailers or other transportation carriers. In most instances such prior art jack bars have a single predetermined maximum length with their adjustment being limited by the range of the jack mechanism. This limits their utilization in that each jack bar can only be used within a relatively small distance range between the wall and the cargo. Thus a number of jack bars with different ranges must be kept on hand to accommodate these differences. Further, most prior art jack bars utilize circular tubes which are telescopically fitted into each other. The use of circular tubes has the disadvantage of permitting the tube members to rotate relative to each other which can hamper the security of the holding action. A jack bar which has a greater range of longitudinal adjustment than most prior art jack bars is described in U.S. Pat. No. 3,995,565 issued on Dec. 7, 1976 to Kersey. In the Kersey device an outer circular tube member is mounted on an inner circular tube member being urged out of the inner member by means of springs. While providing increased range over most prior art jacks, this device still has considerably less range than to be desired. Further, the use of circular tubing has the disadvantage set forth above. In addition, the use of springs has the disadvantage of decreased tension with usage and the possibility of spring breakage.
The device of the invention overcomes the shortcomings of the prior art in providing a much greater range of longitudinal adjustment while avoiding the possibility of rotation of the tube members relative to each other.
The device of the present invention employs a central tube member having a rectangular cross section. One end of the central tube member is attached to a first end piece of the jack bar; this first end piece abuts against the wall of the compartment in which cargo is stowed or the side of cargo to be held in position. A second rectangular tube member is telescopically fitted within the central tube member. One surface of the central tube member is ratcheted and a handle operated ratchet drive mechanism is mounted on the end of the second tube member towards the first end piece. The second tube member is fitted within a third tube member having a rectangular cross section. The remote end of the third tube member is attached to a second end piece on the end of the jack bar opposite that to which the first end piece is attached. As for the opposite end piece the second end piece abuts either against a compartment wall or the cargo or other object in the compartment.
The third tube member has a plurality of sets of opposing apertures along the side walls thereof, these apertures being located at predetermined spaced apart positions along the length of the third tube member. The second tube member has a single pair of opposing apertures formed in the side walls thereof. The second and third tube members are joined together by a snap pin fitted through the apertures of the second tube member and any one of the pairs of apertures of said third tube member. In this manner the length of the jack bar can be adjusted to a desired position over a wide length. In retaining the cargo in position, the ratchet drive mechanism is actuated by means of its handle to drive the ratchets of the second tube to increase the length of the jack bar so as to tighten it between the compartment wall and the cargo or other object being retained in position.